Thermostat device with over temperature safety means



Dec. 7, 1965 H. J. TYLER 3,222,483

THERMOSTAT DEVICE WITH OVER TEMPERATURE SAFETY MEANS Original Filed Dec. 28, 1959 I42 INVENTOR.

HUGH J. TYLER BY QMZQm/w ATTORNEY United States Patent 3,222,483 THERMOSTAT DEVICE WITH OVER TEMPERA- TURE SAFETY MEANS Hugh J. Tyler, Jeannette, Pa., assignor to Robertsllaw Controls Company, a. corporation of Delaware Original application Dec. 28, 1959, Ser. No. 862,153, now Patent No. 3,143,620, dated Aug. 4, 1964. Divided and this application Mar. 12, 1964, Ser. No. 356,685 4 Claims. (Cl.'200140) This application is a divisional application of application Serial No. 862,153, filed December 28, 1959, now Patent No. 3,143,620.

This invention relates generally to a thermostat for controlling the temperature of a fluid and more particularly to a thermostat for controlling temperature varying devices immersed in a fluid.

It is an object of this invention to construct a simple, compact and reliable thermostat for controlling temperature varying devices permitting economy of manufacture and facilitating installation and repair.

Another object of this invention is to incorporate a conveniently accessible temperature setting means in a device of the indicated type.

Another object of this invention is a rugged and compact hydraulic sensing means for a device of the indicated type.

A further object of this invention is to incorporate safety linkage in a thermostat for controlling a temperature varying device to prevent damage at an overtemperature condition.

Still another object of this invention is to construct a thermostat for controlling a temperature varying device which is mounted in a relatively narrow casing, so that two or more thermostats can be placed side by side for multiple thermostatic control in a minimum of space.

In a preferred embodiment of the invention, the thermostat is mounted on and adjacent to an immersion heater unit. A unitary structure is provided wherein an electric heating means is carried on a plug member which can be mounted in the wall of the container of the fluid to be heated so that the heating means is immersed in the fluid. A well member is also mounted on the plug member so as to immersed in the fluid when the plug member is located in the Wall of the fluid container. A thermally responsive means is mounted on a frame and has a temperature sensing means extending into the well member. The thermally responsive means operates a switch is accordance with the temperature variations of the fluid. By this arrangement, a simple, compact and unitary structure is provided.

Although the preferred embodiment of the thermostat has been described above relative to an immersion heater unit, it will be understood that a refrigerating unit can be readily substituted for the immersion heater unit without departing from the spirit of the invention. The use of a double-throw switch is contemplated, which switch will actuate a refrigerating unit, as increased temperatures of the fluid are sensed.

Other objects and arrangements of the invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein the same structural members have been assigned the same reference numerals.

In the drawings:

FIG. 1 is an elevational view, partly in section, of a preferred embodiment of this invention;

FIG. 2 is an end view of the thermostat and switch shown in FIG. 1;

FIG. 3 is a plan view of the device shown in FIG. 2 taken along the line III-III.

Referring more particularly to FIGS. 1-3, the immersion heater thermostat comprises a thermally responsive means 10 mounted on a frame 12 with linkage 14 operatively connecting the thermally responsive means 10 to switch 16. An annular plug member 18 is secured at its outer end 20 by welding or other suitable means to frame member 22 and is adapted to be threadedly mounted in an opening 23 in the container wall 24 of the fluid 26 to be heated. A tubular well member 28 is secured at one end to the inner wall 30 of plug member 18 and depends therefrom to be immersed in fluid 26. An end wall portion 34 serves to close the immersed end of well member 28.

A U-shaped electric heating element 36 also depends from plug member 18 and extends around well member 28 from a pair of insulators 38 carried by plug member 18. A tubular sheath 40 covers the portion of heating element 36 immersed in fluid 26. The opposite ends 42 and 44 of heating element 36 extend from the outer end 20 of plug member 18 and are connected to a pair of terminals 46 and 48, respectively.

Thermally responsive means 10 senses the temperature of fluid 26. Such means comprises a tubular temperature sensing bulb 52 projecting within well member 28 and having a sealed end 54 and the other end threadedly secured to a cylindrical mounting stud 56, such as by soldering 57 or other suitable means. An expansible and contractible element 58 is mounted on stud member 56. Expansible and contractible element 58 comprises an outer cup-shaped member 62 and an inner cup-shaped member 64 nested within outer member 62 and joined at their outer peripheries to form a liquid tight seal. The base of inner member 64 is secured to stud member 56 and has a central opening 66 communieating with a bore 68 in stud member 56.

The face of cup-shaped outer member 62 is secured to an outer stud 76, and has a central opening 70 communieating with a bore 74 in outer stud member 76. Bore 74 is sealed by welding a ball 72 in place after a fillingj operation, wherein a temperature sensing fluid is injected into passage 74 to fill the passageway defined by boresv The temperature sensing fluid is such that it will vary in volume in response .to

68 and 74 and sensing bulb 52.

temperature changes. Since a closed system isformed after the filling operation, it will be apparent that in response to an increase in the temperature of the fluid in the temperature sensing bulb 52, the fluid volume increases and fluid is forced into the space between members 62 and 64. This will cause a separating movement of members 62 and 64 whereby outer member 62 moves outwardly of stud member 56. The ball 72 mounted on the outer stud 76 is displaced directly proportional to the movement of outer member 62, for a purpose to be.

described hereinafter.

Means are provided within temperature sensing bulb 52 to reduce the temperature sensitivity of bulb 52 in the section extending within plug member 18 by minimizing the volume of the temperature sensing fluid in this area. Such means takes the form of a plug 78 which is maintained in the outer portion of temperature sensing bulb 52 by a straight knurled section 80 which has a diameter slightly greater than the inner diameter of bulb 52. A plurality of passages are formed between the inner wall of sensing bulb 52 and the serrations of knurled section 80 to permit fluid flow. The outer diameter of unknurled portion of plug 78 is slightly less than the inner diameter of temperature sensing bulb 52 to permit the pasage of the temperature sensing fluid therebetween.

Thermally responsive means 10 is mounted on anouter 83 in the base 84 of outer frame member 82. Thermally responsive means 10 is locked in position by means of a lock nut 86 which fits on a threaded portion of mounting stud 56.

Outer frame member 82 is connected with frame member 22 by means of a mounting bracket 88, which has a generally U-shaped construction. The base 39 of mounting bracket 88 has an opening 91 which is adapted to receive mounting stud 56. A nut 90, threaded onto mounting stud 56, rigidly secures the assembly including thermally responsive means 10 and outer frame member 82 to mounting bracket 88. Mounting bracket 38 is connected to frame member 22 by means of a pair of screws 92 and 93 threadedly engaging holes 94 and 95, respectively, in frame member 22 and extending through holes in cooperating flanges 96 and 98 on mounting bracket 88.

A circuit means is provided for connecting heating element 36 to a source of electric energy. To this end, a first conductor 100 has one end connected to terminal 48 and the other end adapted to be connected to a source of electric energy. A second conductor 192 is connected between terminal 46 and terminal 104 of a doublethrow switch 16 of a suitable type. A third conductor 106 has one end connected to a terminal 138 of doublethrow switch 16 and the other end adapted to be connected to a source of electric energy. As is well known in the art, terminal 104 is connected to one contact arm (not shown) within the switch casing 110 of switch 16 and terminal 108 is connected to another contact arm (not shown) within casing 110 so that switch 16 is serially connected to the means for heating element 36.

Switch 16 is rigidly mounted to the side members 120 of U-shaped outer frame member 82 by means of a pair of bolts 112 and 114 extending through holes 116 and 118, respectively, in switch casing 110. A switch button 122 is mounted for axial movement through a wall 124 of switch casing 110 facing thermally responsive means 10 and is biased to extend outwardly of wall 124. Double-throw switch 16 can be of any suitable type wherein the movement of switch button 122 inwardly of casing 110 causes opening of the switch contacts (not shown) and movement of switch button 122 in the opposite direction causes closing of the contacts. Hence, the position of switch button 122 will control the opening and closing of the circuit to heating element 31 Snapacting switches are one type of switch well known in the art which will operate in this manner.

An operative linkage connection 14 is provided between thermally responsive means 10 and switch 16 to actuate the latter between the circuit opening and circuit closing positions thereof in response to the thermally responsive movement of thermally responsive means 11 Such operative linkage connection comprises a lever arm 126 having a longitudinally extending end portion 128. The opposite end of lever arm 126 is formed with laterally extending projections 130. Lever arm 126 is positioned to engage ball 72 at an intermediate point and with the lateral extremities of projections 1319 engaging a pair of oppositely disposed fulcrums 132 formed in a pair of oppositely disposed cutouts 134 in the sidewalls of a U-shaped adjusting yoke 136.

A flat spring 138 is substantially rigidly connected by a tongue and groove means to adjusting yoke 136 at 1411. Flat spring 138 is biased in a clockwise direction by lateral sections 142 being forced into cutout sections 143 of side members 120. An adjusting screw 144 is threaded into offset member 145, formed from the bight portion of U-shaped adjusting yoke 136, and is biased by adjusting yoke 136 in a clockwise direction to engage frame 82 at point 146. Turning adjusting screw 144 thereby pivots adjusting yoke 136 about point 141 to vertically displace fulcrum 132 to adjust the setting of the thermostat. It will thus be apparent that lever arm 126 pivots about fulcrums 132 in response to expansion and contraction of e ement 3,

A dial plate 148 is provided to indicate the temperature setting of the thermostat. A pointer is provided on adjusting screw 144 by a dot of paint 150, which cooperates with a dial plate 143 to indicate the temperature setting.

In operation, after the immersion heater unit has been assembled in container wall 24, temperature adjusting screw 144 is rotated to the desired temperature setting position in accordance with the marking thereon. Temperature sensing bulb 52 will sense an increase in the temperature of fiuid 26 and the temperature sensing fluid contained therein will be expanded accordingly. If the temperature of fluid 26 is below the desired temperature, expansible and contractible element 58, acting through ball 72, will position lever arm 126 so that switch button 122 will be maintained in the switch closed position thereof, thereby completing the circuit to heating element 36.

As the temperature of fluid 26 is raised by the heating action of heating element 36, element 53 expands as the increased volume of the temperature sensing fluid causes fluid to be forced into the space between members 62 and 64. The expanding movement of element 58 causes lever arm 126 to pivot in a clockwise direction about fulcrums 132, thereby forcing switch button 122 inwardly. When the desired fluid temperature is reached, element 58 will have caused sufficient clockwise movement of lever arm 126 to force switch button 122 to the switch open position, whereby the circuit to heating element 36 is broken.

If the temperature of fluid 26 should continue to increase after the circuit to heating element 36 has been broken, switch button 122 will then function as the fulcrum for lever arm 126. Hence, as element 58 expands, lever arm 126 overcomes the force of spring 138 and rotates in a counterclockwise direction to lift the adjusting screw 144 away from its contact point 146 on frame 82. This action allows fulcrum points 132 to rise when a predetermined force against ball '72 is reached and thereby does not limit the expansion of expansible and contractible element 58 due to overtemperature conditions of fluid 26. Thus, damage to expansible members 62 and 64 is prevented.

As the fluid temperature decreases from the overtemperature condition, fulcrums 132 will assume their normal position when temperature adjusting screw 144 touches at point 146 on frame 82. If the temperature of fluid 26 should decrease, then a corresponding decrease in the volume of the temperature sensing fluid permits contraction of element 53. Lever 126 will thus be rotated in a counterclockwise direction about fulcrums 132 under the action of switch button 122 which will gradually move toward the switch closing position in accordance with its outward bias. When switch button 122 reaches the switch closed position, the circuits to heating element 36 will be again closed.

The immersion heater unit Will cycle in the above manner to maintain fluid 26 at the desired temperature.

It will be apparent that the described construction forms a simple, compact and reliable thermostatic unit, wherein the unit can easily be replaced if damaged without entering the container, and the temperature setting means and the wiring terminals are conveniently accessible even though several switch units are mounted side by side and very close together.

In addition, the described construction forms a thermostatic unit which has an overtemperature safety linkage to prevent damage to component elements of the unit.

Although a single embodiment of this invention has been shown and described for purposes of illustration as controlling heating units, it is to be understood that the invention can be variously embodied to control either heating or cooling units. Changes may be made in the construction and arrangement of parts without departing from the scope of the invention as defined by the appended claims.

I claim:

1. In a temperature responsive device for sensing the temperature of a fluid in a container, the combination comprising first means for mounting a well member within a container, frame means secured to said first means, temperature responsive means mounted on said frame means and having temperature sensing means connected thereto and extending into said well member for actuating said temperature responsive means, switch means mounted on said temperature responsive means by a support member, a fulcrum member biased into engagement with said support member, a lever pivoted at one end about said fulcrum member and positioned to engage at an intermediate portion with said temperature responsive means, a switch actuating button for actuating said switch means engaging the opposite end of said lever, said temperature responsive means having a first range of movement causing pivotal movement of said lever about said fulcrum member to actuate said switch button, said temperature responsive means having a second range of movement causing pivotal movement of said lever about said switch button to move said fulcrum member out of engagement with said support member whereby said second range is an abnormal temperature control.

2. In a temperature responsive device for sensing the temperature of a fluid in a container, the combination comprising first means for mounting a well member within a container, frame means secured to said first means, temperature responsive means mounted on said frame means and having temperature sensing means connected thereto and extending into said well member for actuating said temperature responsive means, a support member having legs and secured to said temperature responsive means, switch means mounted between the legs of said support member, a switch actuating button for actuating said switch means, a yoke member spring biased into engagement with the bight portion of said support member and having legs with fulcrums therein, a lever pivoted at one end between said fulcrums in the legs of said yoke member and positioned to engage at an intermediate portion with said temperature responsive means with the opposite end of said lever engaging said switch button, said temperature responsive means having a first range of movement causing pivotal movement of said lever about the fulcrums of said yoke member to actuate said switch button, said temperature responsive means having a second range of movement causing pivotal movement of said lever about said switch button to move said yoke member out of engagement with said support member whereby said second range of movement is an abnormal temperature control.

3. A temperature responsive control device comprising: frame means, temperature responsive means mounted on said frame means including a temperature sensing means connected thereto, said temperature responsive means having a movable portion thereof which moves with changes of temperature sensed by said temperature sensing means, a fulcrum member biased into engagement with said frame means, switch means fixedly mounted relative to said temperature responsive means and includ ing a switch actuating buttton, a lever pivotally mounted at one end to said fulcrum member and positioned for engagement at an intermediate portion by said movable portion of said temperature responsive means and at the opposite end by said switch actuating button at the 0pposite end of said lever whereby said movable portion of said temperature responsive means is effective when moved in one direction in response to temperature sensed by said temperature sensing means to pivot said lever to move said switch actuating button until said switch actuating button reaches the limit of its travel, any further movement of said movable portion in said one direction then being effective to pivot said lever about said switch actuating button causing said one end of said lever to move said fulcrum member out of its biased engagement with said frame means.

4. A temperature responsive control device comprising: frame means, temperature responsive means including a temperature sensing means connected thereto, said temperature responsive means having a movable portion thereof which moves with changes of temperature sensed by said temperature sensing means, a yoke member having legs, a spring member connected between said frame means and said yoke member and biasing said yoke member into engagement with said frame means, switch means fixedly mounted relative to said temperature responsive means and including a switch actuating button, a lever positioned between the legs of said yoke member and pivotally mounted thereto at one end, said lever engaging said movable portion of said temperature responsive means at an intermediate portion on one side of said lever and engaging said switch actuating button on the other side of said lever at the other end of said lever whereby movement of said movable portion of said temperature responsive means in one direction due to said temperature sensing means responding to a temperature which rises to a point above the set temperature for the device is etfective to first pivot said lever about said one end and move said switch actuating button until said button reaches the limit of its travel and then pivot said lever about said switch actuating button causing said one end of said lever to move said yoke member out of its biased engagement with said frame means.

References Cited by the Examiner UNITED STATES PATENTS 2,460,762 2/1949 Minnich 200- 2,809,523 10/1957 Burling et al. 200-137 2,924,388 2/1960 Beck et al. 200-140 BERNARD A. GILHEANY, Primary Examiner. 

1. IN A TEMPERATURE RESPONSIVE DEVICE FOR SENSING THE TEMPERATURE OF A FLUID IN A CONTAINER, THE COMBINATION COMPRISING FIRST MEANS FOR MOUNTING A WELL MEMBER WITHIN A CONTAINER, FRAME MEANS SECURED TO SAID FIRST MEANS, TEMPERATURE RESPONSIVE MEANS MOUNTED ON SAID FRAME MEANS AND HAVING TEMPERATURE SENSING MEANS CONNECTED THERETO AND EXTENDING INTO SAID WELL MEMBER FOR ACTUATING SAID TEMPERTURE RESPONSIVE MEANS, SWITCH MEANS MOUNTED ON SAID TEMPERATURE RESPONSIVE MEANS BY A SUPPORT MEMBER, A FULCRUM MEMBER BIASED INTO ENGAGMENT WITH SAID SUPPORT MEMBER, A LEVER PIVOTED AT ONE END ABOUT SAID FULCRUM MEMBER AND POSITIONED TO ENGAGE AT AN INTERMEDIATE PORTION WITH SAID TEMPERATURE RESPONSIVE MEANS, A SWITCH ACTUATING BUTTOM FOR ACTUATING SAID SWITCH MEANS ENGAGING THE OPPOSITE END OF SAID LEVER, SAID TEMPERATURE RESPONSIVE MEANS HAVING A FIRST RANGE OF MOVEMENT CAUSING PIVOTAL MOVEMENT OF SAID LEVER ABOUT SAID FULCRUM MEMBER TO ACTUATE SAID SWITCH BUTTOM, SAID TEMPERATURE RESPONSIVE MEANS HAVING A SECOND RANGE OF MOVEMENT CAUSING PIVOTAL MOVEMENT OF SAID LEVER ABOUT SAID SWITCH BUTTOM TO MOVE SAID FULCRUM MEMBER OUT OF ENGAGEMENT WITH SAID SUPPORT MEMBER WHEREBY SAID SECOND RANGE IS AN ABNORMAL TEMPERATURE CONTROL. 